CASIO CT870
Manual de Servicio

DIGITAL SIGNAL PROCESSOR (LSI102: HG51B277FB)
The DSP receives 16-bit serial sound data output from the CPU and adds the selected effect to the sound data using the effect RAM. Then the DSP provides the sound data to the DAC. The DSP contains two I/O ports, which controls LEDs. The following table shows the pin functions of LSI102.

Pin No. 1 ~ 4, 80 5 6 7 8 9 10 11, 12 13 14 15 16 17 18 ~ 25 26 27 28 29 30 31 32 33 34 35 ~ 41, 43 42, 44, 46 ~ 48, 51 ~ 57, 59 45 49 50 58 60 61 62, 66, 70, 74, 78 63, 67, 71, 75, 79 64, 65, 68, 69, 72, 73, 76, 77

Terminal PB0 ~ PB4 SO WCKO VDD3 TEST RESB VSS2 XIN, XOUT WCKI SI BCKI SINC VDD2 IO0 ~ IO7 RCEB VSS3 AD1 OEB WEB VDD3 CE2 AD0 CE1B EIO0 ~ EIO7 EA0 ~ EA12 ECEB EOEB VSS3 EA13 EWEB EA14 VSS2 VDD2 PA0 ~ PA7

In/Out Out Out Out In � In In In/Out In In In In In In/Out Out In In In In In In In In In/Out Out Out Out In Out Out Out In In Out

Function LED drive signal output Serial sound data output for the DAC Word clock output for the DAC +5 V source Not used. Reset signal input Ground (0 V) source 16 MHz clock input/output Word clock input from the CPU Serial sound data input from the CPU Bit clock input from the CPU 1 MHz synchronizing pulse input +5 V source Data bus Chip enable signal output for the working storage RAM Ground (0 V) source Address bus Not used. Connected to +5 V source. Write enable signal input +5 V source Chip enable signal input. High active. Address bus Chip enable signal input. Low active. Data bus for the effect RAM Address bus for the effect RAM Chip enable signal output for the effect RAM Read enable signal output for the effect RAM Ground (0 V) source Not used Write enable signal output for the effect RAM Not used Ground source +5 V source LED segment signal output

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